[Coco] the bit-banger

[Chuck Youse]

Does anybody _really_ use this in a *S9 setup?  I'm sorely tempted to
disconnect the interrupt line (SERINT) from the GIME chip in my system
and hook it to the cartridge port so I can generate FIRQ* from the
expansion bus... and no, I can't just tie the interrupt to FIRQ*
directly, I need a means to enable/disable the interrupt individually.
The ability to dynamically change it between FIRQ* and IRQ* is also
ridiculously useful (for the FDC anyway).

Mind you, _I_ don't use the bit-banger (I use a UART for RS-232, use of
the bit-banger REALLY eats CPU cycles), but I'd rather find the
least-intrusive mod for others who might want to use this FDC ..

I'll also see if using the interrupt mechanism on PIA1 is feasible.

C.